Motorola SG 2000 用户手册
5 - 2 2 O p e r a t i o n
SG 20 00 Ins tal la tion and O pera tion M anua l
D S -S G2 -D RT -2X /A D ig ita l Re tu rn T ran smitter
The DS-SG2-DRT-2X/A is an SG2 return transmitter that digitizes two independent analog
5 MHz-42 MHz return-path signals to produce two 1.25 Gbps data streams. These two data streams
are then multiplexed to create a 2.5 Gbps data stream. This data stream is then routed to a digital
laser for transmission to a corresponding digital return receiver.
5 MHz-42 MHz return-path signals to produce two 1.25 Gbps data streams. These two data streams
are then multiplexed to create a 2.5 Gbps data stream. This data stream is then routed to a digital
laser for transmission to a corresponding digital return receiver.
The transmitter can be configured with a digital laser wavelength that is applicable to the required
link length. An APC system regulates the optical output power from the laser. Two user-accessible
input level-control adjustments enable you to independently adjust the transmitter input levels
link length. An APC system regulates the optical output power from the laser. Two user-accessible
input level-control adjustments enable you to independently adjust the transmitter input levels
+
2 to
−
13 dB from an input level of 15 dBmV. All transmitter status-monitor information is available at
the digital return receiver.
To facilitate easy upgrades, the DS-SG2-DRT-2X/A fits the same footprint and has the same set-up
levels as the analog return transmitters.
levels as the analog return transmitters.
Figure 5-23 illustrates a block diagram of the DS-SG2-DRT-2X/A:
F i g u r e 5 - 2 3
D S - S G 2 - D R T - 2 X / A
D S - S G 2 - D R T - 2 X / A
Serializer
Transmit
signal
processing
logic
A/D
converter
RF
XFMR
XO
XO
Anti-
aliasing
LPF
Return
band RF
5-42 MHz
CATV
gain block
A/D
converter
RF
XFMR
Anti-
aliasing
LPF
Return
band RF
5-42 MHz
CATV
gain block
Digital
lightwave to
SG2 output
Optical transmitter module
Serial bit
stream
@2.5 Gbps
Figure 5-24 illustrates the DS-SG2-DRT-2X/A and attached cable:
F i g u r e 5 - 2 4
D S - S G 2 - D R T - 2 X / A
D S - S G 2 - D R T - 2 X / A
INPUT
A
INPUT
B
STATUS DS-SG2-DRT-2X/A
1310 DFB
RF
INPUT
B
SG2000
Digital Transmitter
DANG
E
R
Test
Point
A
Test
Point
B
You can gain access to test point A through the transmitter test cable MCX-F (DS-SG2-DRT-TC,
P/N 476803-001).
P/N 476803-001).